Chiral response of twisted bilayer graphene

I will present an effective (minimal) theory for chiral two-dimensional materials. These materials possess an electro-magnetic coupling without exhibiting a topological gap. As an example, I will discuss the response of doped twisted bilayers, unveiling unusual phenomena in the zero frequency limit: an in-plane magnetic field induces a huge paramagnetic response at the neutrality point and, upon doping, also gives rise to a substantial longitudinal Hall response. At finite frequencies, the system accommodates nontrivial longitudinal plasmonic modes which are associated with a longitudinal magnetic moment, thus endowing them with a chiral character.